What Is Prurigo Nodularis and How to Recognize It

Prurigo nodularis is an inflammatory skin condition that causes the development of intensely itchy skin and bumps or lumps (nodules) on the legs, arms, upper back, or abdomen.

This article discusses the appearance, symptoms, and treatment options for prurigo nodularis.

What Is Prurigo Nodularis?

Prurigo nodularis is a chronic skin condition that can develop independently or in relation to another health disorder. The nodules that develop are so itchy that people with prurigo nodularis often experience other issues, such as sleep disturbances and psychological distress. Extreme itchiness can also drive people to scratch an area so long that it becomes painful or bleeds.

What Does It Look Like?

The bumps that form because of prurigo nodularis are firm to the touch and take on a dome-like shape. If it weren’t for the extreme itchiness, prurigo nodularis could be mistaken for warts because of how similar they look. While the bumps start at roughly the size of a pinpoint, they can grow to be the same size as a quarter.  

As the itchiness sets in and you scratch the rash, your rash will continue to worsen and the nodules will continue to multiply on the skin. You can have just a few or hundreds of bumps in the affected area. Typically, the nodules develop symmetrically, so they would appear the same on both the left and right sides of the body regardless of where the rash occurs.

Colors of the nodules include:

• The same color as your skin
• Pink
• Red
• Brownish black

Types 

There are two types of prurigo nodularis: primary and secondary.

Primary prurigo nodularis develops independently without the presence of another health condition, whereas secondary prurigo nodularis occurs when you have another health or skin disorder that is driving symptoms.

What Are the Symptoms of Prurigo Nodularis?

The main symptom of prurigo nodularis is intensely itchy skin. The scratching that follows leads to the development of bumps within six or more weeks.

Other symptoms can also develop because of the uncontrollable scratching, including:

• Burning or stinging skin
• Bleeding and lesions caused by scratching
• Dark spots
• Light spots
• Scarring

What Causes Prurigo Nodularis?

There is no known cause of primary prurigo nodularis. Medical researchers believe that the immune system plays a role in the itchiness, which leads to scratching and, eventually, the nodules forming.

While more research is needed, it's thought that inflammation caused by an immune system malfunction and pro-inflammatory substances in the body contributes to the development of prurigo nodularis. Scratching can also thicken nerves in the skin, leading to the development of nodules.

When a person has secondary prurigo nodularis, any number of health disorders, such as the ones mentioned above, could be causing the condition.

How Is Prurigo Nodularis Diagnosed?

To diagnose prurigo nodularis, a dermatologist will conduct a clinical exam. The examination is designed to:

• Collect health history
• See the rash and gather information about the symptoms
• Rule out other skin disorders

A dermoscopy and skin biopsy will be performed along with a physical exam and a review of your health history. During the dermoscopy, the medical provider will use a magnifying scope with a light attached to get a better look at the skin structure. A biopsy takes a sample of the affected skin area so that it can be investigated under a microscope for any signs of prurigo nodularis.

How Is Prurigo Nodularis Treated?

Treating prurigo nodularis isn’t as straightforward as other skin disorders because there has been minimal research in this area. Therapy for the condition is based on several factors, including:

• Age
• Coexisting conditions
• Severity
• Quality of life
• Possible medication side effects

Dupixent (dupilumab) is the first, and only Food and Drug Administration (FDA) approved medication for the treatment of adults with prurigo nodularis. Because of the factors to consider during treatment, choosing the proper therapy will be done with your healthcare provider after discussing your options. Typically, treatments for prurigo nodularis include:

• Triamcinolone acetonide (a type of corticosteroid) injections
• Cryotherapy, which freezes the bumps so they can be removed
• Topical corticosteroids
• Hydrocortisone creams
• Herbs that help with the itch, such as feverfew
• Topical calcineurin inhibitors
• Vitamin D analogs
• Antihistamines
• Phototherapy (light therapy)
• Oral immunosuppressant medications (for the most severe cases only)
• Opioid blockers such as naloxone
• Antinausea and anti-vomiting drugs (NK1r antagonists)

Each medication is designed to control the itching sensation so that you can find relief and limit scratching. While the goal is the same, each drug works in the body differently. People with prurigo nodularis must speak to their healthcare provider about all their options to determine which is right for them.

When to See a Healthcare Provider

See a healthcare provider if you experience itchy skin on any area of the body and it feels impossible not to scratch it. Your provider will help determine what is causing the sensation and work with you to find a treatment.

Summary

Prurigo nodularis is a chronic, inflammatory skin condition that develops over several weeks. You will notice the itch first, but the more you scratch, the more damage the skin will endure. After a while, bumps or nodules start to form. The spots begin small but can progress to be as large as a quarter. People may also experience burning, bleeding, and lesions in the area caused by scratching. There is no known cause for prurigo nodularis, but an underlying health disorder is the reason for most cases.

To rule out other skin disorders, your doctor will perform a skin biopsy or dermoscopy alongside a physical examination. Many treatment options are available, but diagnosing prurigo nodularis and any possible co-occurring conditions has to come first. Contact a healthcare provider if you experience intense itchiness on any area of your body that affects your day-to-day life.